Playing apparatus for musical instruments.



W. G. REED.

I PLAYING APPARATUS FOR MUSICAL INSTRUMENTS.

APPLIOATION FILED AUG. 23, 1910.

1,1 1 6,327. Patented Nov. 3, 1914.

4 SHEETS-SHEET 1.

Mm, a w,

W. G. REED.

PLAYING APPARATUS FOR MUSICAL INSTRUMENTS.

APPLICATION FILED AUG.23, 1910.

1,11 6,827, Patented Nov. 3, 1914.,

4 SHEETSSHEET 2.

WIT EEEEAA NEH-m 1 WWWAM,

' wwww,

W. G. REED.

PLAYING APPARATUS FOR MUSICAL INSTRUMENTS.

APPLIGATION FILED AUG.23, 1910.

Patented Nov. 3, 1914.

4 SHEETSSHEET'3.

WI 0. REED. PLAYING APPARATUS FOR MUSICAL INSTRUMENTS.

APPLICATION FILED AUG.23, 1910. 1,1 1 6,327, Patented Nov. 3, 1914.

4 SHEETS-SHEET 4.

A u/AAAUJAM. Q g/jw EQMM,

UNITED STATES PATENT OFFICE.

WALTER C. REED, OF DALTON, MASSACHUSETTS, ASSIGNOR TO THE TELELECTRIG COMPANY, OF PITTSFIELD, MASSACHUSETTS, A CORPORATION OF MASSACHU- SETTS.

PLAYING APPARATUS FOR MUSICAL INSTRUMENTS.

To all whom it may concern Be it known that I, WALTER C. R EED, a citizen of the United States, residing at Dalton, in the county of Berkshire and State.

of Massachusetts, have invented certain new and useful Improvements in Playing Appara-tus for Musical Instruments, of which the following is a specification.

This invention relates to automatic playing apparatus for; pianos and other keyoperated musical instruments in which the keys are struck by means of electrically-energized playing magnets, included in parallel circuits having variable resistance therein for regulating the loudness of the tones produced, and is particularly intended to provide an arrangement of Variable resistances and devices for controlling the same which may be employed in connection with the form of music sheet shown and described in U. S. Letters Patent No. 1,058,902, granted on the 15th day of April, 1913, for the purpose of differentiating one or more notes of a composition, with respect to their loud ness, from one or more other notes struck at the same time, or substantially so, in order to contrast the melody of thecomposition with the accompaniment, for example, and thus bring out the intended expression of the composition as a whole. To this end, the resistances included in the playingmagnet circuits are provided respectively with one or more shunts or branch circuits, and each of these branch circuits includes a sensitive or quickly-acting circuit-control ling device operated by an electro-magnet which is included in an independent circuit controlled by a special perforation or series of perforations in the music sheet, the ar- 'Iangement being such that when any given branch circuit is closed a certain portion of the corresponding resistance is short-circuited, so that the strength of the current sent through the corresponding playing magnet is increased accordingly. This arrangement may be and preferably is employed in connection with sliding contact ngers such as have heretofore been employed for varying the resistances in the playing-magnet circuits, this being desirable for the reason that the sliding contact fingers can be operated to vary the resistance to any desired extent and thus secure slight variations in the loudness of the tones produced, while a resistame-varying arrange- Specification of Letters Patent.

' Patented Nov. 3, 1914.

Application filed August 23, 1910. Serial No. 578,587.

,ness of the notes generally, whether the slidin contact fingers are employed or not.

11 order that a considerable variety of resistance eifects may be produced, each of the resistances is preferably provided with two or more branch circuits arranged to throw different amounts of resistance into or out of the corresponding playing-magnet circuit, so that by opening or closing the branch circuits, either individually multaneously, various combinations of the parts into which the resistances are dividedmay be included in the playing-magnet circuits and caused to vary the strength of the energizing current accordingly. The circuit-controlling devices which are included in the various branch circuits are prefer- .ably so grouped that the bass notes and the throw a large amount of resistance into the playing-magnet circuits and thereby subdue the loudness of the tones produced.

In the accompanying drawingsthe invention is illustrated as applied to or embodied in a playing apparatus which, except as hereinafter explained, may have substantially the same construction and mode of operation as the playing apparatus shown and described in U. S. Letters Patent No. 753,809, dated March 1, 1904, to Powers and Jewell, to which Letters Patent reference may be made for a full understanding of the various parts and details which are included in the complete apparatus but are not specifically described herein, the present drawings bein largely diagrammatic 1n character and i lustrating only such parts of the or siprior apparatus as are necessary for an understanding of the invention. In these drawings: Figure 1 is a diagram showing the preferred arrangement of the electric circuits; Fig. 2 is a diagram .showing certain of the electric circuits corresponding to a single playing magnet; Fig. 3 is a top plan view illustrating one form of mechanism for opening and closing shunt circuits hereinafter described; ig. 4 is a transverse section on the line 4--4 in Fig. 3;. Fig. 5 is a longitudinal section through the contact cylinder shown in Fig. 3 and hereinafter described; Fig. 6 is a diagram similar to Fig. 2, but illustrating another form of circuit-controlling mechanism; Fig. 7 is a top plan view of the circuit-controlling mechanism shown in Fig. 6; and Fig. 8 is an elevation of the parts shown in Fig. 7, as viewed from the right of said figure;

Referring particularly to Fig. 1, the parts shown therein include a metallic contact bar 2, parallel circuits 3 each extending therefrom to a common return wire 4 and including a playingmagnet 5, a source of electric current such as a battery 6, to one terminal of which the common return wire 4 is connected, and a wire 7 leading from the other terminal of the battery 6 to the contact bar 2 and including a switch 8 which controls the operation of the apparatus as a whole. A circuit 3, including a playing magnet 5, is provided for each piano key which is to be operated bythe apparatus, but inasmuch as these circuits and playing magnets are precisely alike only four of them are shown in Fig. 1, and of these four playing magnets, two are assumed to be connected to bass keys of the keyboard and the other two are assumed to be connected to treble keys. Each of the circuits 3 also includes a suitable contact device under the control of the perforated music sheet, whereby the several circuits are opened and closed at the con-' tact bar 2 according to the notes to be played, the arrangement for this purpose which is shown at 9 in Fig. 2 being constructed as shown and described in the Powers and Jewell patent previously referred to. In each of the: circuits .3 is also included a resistance which is divided into different portions and preferably these portions are of different lengths. The number and length of these portions may be varied as desired, but in the arrangement represented in the drawings there are three of these portions, indicated at 10, 11 and 12 respectively, and their lengths are in the ratio of 3, 4 and 2. In Fig. 1 the ortions 10, 11 and. 12 are shown as somewh arated, for the sake of clearness of illustration, but this is not essential, and they are commonly arranged to form a continuous the at sepamass? series of-equi-distant coils, as indicated in Fig. 6. From the opposite ends of each resistance portion 10 branch circuit wires a-a. lead to a circuit-controlling device such as A, hereinafter described, and in like manner branch circuit wires bb lead from the opposite ends of each resistance portion 11 to another circuit-controlling device such as B. According to the arrangement illustrated in Fig. 1 there are two similar circuitcontrolling devices A and also two similar circuit-controlling devices B, one of each for the resistance portions corresponding to the bass playing-magnet circuits and one of each for the resistance portions corresponding to. the treble playing-magnet circuits, each of these circuit-controlling devices being arranged to operate simultaneously on all the branch circuit wires leading from the corresponding group of resistance portions, and each circuit-controlling device is provided with an operating magnet included in an independent circuit which is controlled at the contact bar 2 by a special series of perforations in the music sheet. For example, each circuit-controlling device A has its operating magnet 13 included in a circuit comprising wires 14 and 15 leading respectively from one side" of the magnet to the contact bar 2, where the circuit includes a contact device such as is employed for the playing-magnet circuits, and from the other side of the magnet to a common return wire which may be the return wire 4 but is preferably an independ ent wire 16 joining the wire'4 at 17. In like manner each circuit-controlling device B has its operating magnet 18 included in a circuit comprising wires 19 and 20 leading respectively from one side of the magnet to the common return wire 16 and from the other side of the magnet to the contact bar 2 through one of the contact devices alreadyreferred to. The return wires 4 and 16 are preferably provided with switches 21 and 22, whereby the circuits throu h the same may be opened and closed in ependently of each other.

Two forms of circuit-controlling device are illustrated in the drawings, the device shown at A in Fig. 1 bein illustrated in detail in Figs. 3, 4 and 5. T is form of device consists of a series of alternating metallic disks 23 and insulating disks 24 mounted on a rod or axis 25, the disks 23 being insulated from said red by means of a nonconducting tube 26 surrounding the latter and from one another by means of the disks 24. The disks 24 have a sli%htly greater diameter than the disks 23, so t at a circumferential groove is provided at the periphery of each disk 23 to receive the correspondin branch circuit wires; a-a,. and each dis 23 is provided-at one point of its rarirbe y wit n i ul n pmi c n, hi

. man ac? being preferably accomplished by boring a the disks 23 and into the grooves between the disks 24;. Said disks are clamped firmly together between heads 28 and '29 carried by .the rod 25, and said rod is mounted to oscillate 011 suitablefiiied bearings 30 and 31 car,-

:ried by a base plate 32, Fig. 3, and is operated by means of the armature 33 of the electro-magnet 13, which-armature and magnet may have the same construction as the corresponding parts of the playing magnets 5.- The armature 33 is mounted to turn on the bearing 31 and is connected to the rod by a' pin 34 entering the armature at one end and the head '29- at its other end, and a spring 35 holds said armature in the posi- $1011 shown in Fig. 4 when the circuit through the magnet 13 is open, so that the energizing of. the magnet will result in a partial rotation of the rod 25 One of each pair of circuit wires a -a is held in constant contact with the corresponding metallic disk 23, while the companion circuit wire tends to make contact with the same disk but is normally held out of contact therewith by the insulating bar 27, as shown in 4, thus opening the circuits through the wires a-a. \Vhen the parts are in this position the portions 10 of the corresponding resistances will evidently be included in their circuits 3 and will have their effect on the energizing current sent through such of the cor responding playing magnets 5 as are in closed circuit at that time, but wheneverithe circuit through the magnet 13 is closed the resulting movement of its armature 33 will instantly rotate the rod 25 and the disks thereon to a sufiicient extent to carry the insulating bar 27 out from under all the circuit wires a which are controlled by said.

bar, whereupon the corresponding portions 10 of'the resistances'willbe short-circuited,

and the circuits throu h the corresponding playing magnets will ave their resistance reduced accordingly in case they are closed,

at the contact bar.

All the circuit-controlling devices A and- B are constructed and arranged to operate in the manner just described, and inasmuch as each of them controls but one of thesev eral groups of like resistance portions, different resistance effects may be obtained by operating these devices in various ways, as,

for example, by short-circuiting either.-

group of resistance'portions 10, or either group of resistance portions 11, or both groups conjointly, and the resistance eflects obtained in the circuits corresponding to the the.- entire length corresponding to the bass keys by virtue of the employment. of independent circuit-controlling devices in connectionwith the resistance circuits corresponding to these two divisions of the keyboard.

In connection with the resistances included in the circuits 3 a .set of contact fingers 36, one for each resistance, may also be employed, which fingers are all secured to a bar 37 provided with suitable devices (not shown) .for moving it back and forth in such manner as to slide the fingers 36 along the respective resistances, in contact therewith, thereby cutting out a greater or less number of the coils of which they are composed. A somewhat similar arrangement of contact fingers has heretofore been employed for varying the loudness of all the notes struck ata given time, but according to the prior construction just referred to each resistance is connected with the corresponding playing magnet through the corresponding contact 'finge'r only, in circuit with the playing magnet, while in the apparatus herein represented each resistance is directly in series with the correspondin circuit 3, and the corresponding contact %nger .36 forms a part of a "branch circuit through which the resistance may be short-circuited to an extent depending uponthe position of the finger 36. These branch circuits are opened and closed as desired by means cit-one or more circuit-controlling devices C, of which two are shown in Fig. 1, one for the bass-playing magnet circuits and one for the treble playing-magnet circuits. The

circuit-controll-ing devices 0 are practically identical in construction with the devices A and 3 already described, and their operating magnets 38 are similarly included in spe cial circuits each consisting of a wire 39, leading from one side of the magnet to the return wire 16 and another wire 40 leading from the other side of the magnet to the contact bar 2, where the circuit is controlled by a contact device similar to those employed ,in the other circuits and adapted to be controlled by a special series of perforations in the music sheet. In the case of each of the circuit-controlling devices C, however, the contact; fingers 36 and the circuit wires 3. :are normally in contact with the corresponding metallic disks 23 when the operating magnet 38 is denergized, as shown in Figs, 1 and 2, and the insulating bar 27 is so lo cated that when said magnet is energized the resulting movement of its armature will bring said insulatin bar underthe contact fingers 36 and lift t e same out of contact with the respective disks 23, thus opening the branch circuits in which these contact fingers are included and rendering the same inoperative for the time being. In such case,

the energizingcurrent has to pass through of the provided which contact finger is always 7 that no part of the same is short-circuited at that time, and the arrangement just described thus serves for subduing the loudness of the tones produced by throwing an increased resistance into the playing magnet circuits and thus reducing the current strength accordingly.

In the diagrammatic illustration of the circuit-controlling devices C in Fig. 1, the disks are represented ,as if viewed in the direction of their axes in order to show both the contact fingers 36 and the circuits 3, but it will be understood that the actual arrangement of said disks is the same as that of the corresponding disks in the circuitcontrolling devices A and -B. The operating magnets for all of these circuit-controlling devices are also shown in Fig. 1 as if viewed in an axial direction and each of the circuit wires aa and bb is represented as leading to the corresponding metallic disk in a direction which is radial to the axis of that disk, for the sake of clearness of illustration, the actual arrangement being as shown in Figs. 2 and 4, in which each of said circuit wires occupies a tangential relation to the corresponding disk.

In Figs. 6, 7 and 8 is shown another form of circuit-controlling device which may be employed instead of the devices A and B or either of them. In this form of device any desired number of metallic contact pins 41 are carried by an insulating support 42 mounted on a suitable base 43, and an insulating block 44 is supported from the same base and carries a series of wires one for each pin 41, the free ends of these wires being normally supported on an insulating bar 46 which is carried by and moves with the armature 47 of an electro-magnet 48. The natural spring of the wires 45 tends to move the metallic contact pieces 49, carried thereby, into contact with the corresponding pins 41, but such movement is resisted, so long as the magnet 48 is deenergized, by means of a spring 50 which tends to press the supporting bar 46 upward and is strong enough to slightly overbalance the collective eflect of the wires 45. Two of these circuit-controlling devices are illustrated in Fig. 6, one for the resistance portions 10 and one for the resistance portions 11, and their magnets 48 are adapted to be included respectively in the special circuits formed by the 'wires 14, 15, and 19, 20, Fig. 1, in substitution for the magnets 13 and 18. One of each pair of circuit wires a-a is connected to one of the wires 45 in the circuit-controlling device for the corresponding group of resistance portions, and in like manner one of each pair of circuit wires b-b is connected to one of the circuit wires in the other circuit-controlling device, while the companion wires a and 6 lead from the respective contact pins 41 to the corresponding resistances through wires such as ab, one of which is common to both branch circuits for each resistance, a single wire ab being preferably employed, in practice, instead of two wires leading to the same point of the resistance as shown in Fig. 1. As thus constructed, the circuits through the branch circuit wires H and bb are normally open at the contact pins 41, but when the circuit through either magnet 48 is closed the energizing of the magnet overcomes the over-balancing efiect of the spring 50 and pulls the supporting bar 46 downward, whereupon the pieces 49 instantly make contact with the pins 41 and thus short-circuit the corresponding portions of the respective resistances by'closing the branch circuits around the same. When the circuit through the magnet 48 isopened, however, the supporting bar 46 is instantly raised by the spring 50 and breaks the branch circuits at the contact pins 41.

The circuit-controlling device just described may be adapted for use in substitution for the circuit-controlling devices C by so arranging the contact pins that the circuits through the same are normally closed instead of normally open, but are opened whenever the magnet 48 is energized.

The various circuit-controlling devices abovejdescribed are so sensitive, in the sense of being very quickly operated to open or close the respective circuits which they control, that they make it .possible to control the action of the playing magnets in such manner as to accent or subdue any desired notes of a composition by the employment of the form of music sheet shown and described in U. S. Letters Patent No. 1,058,902, previously mentioned, which operation requires that the strength of the current which energizes the playing magnets shall be altered instantaneously or practically so, and the present improvements are therefore particularly well adapted for use in playing apparatus in which it is desired to secure the tone-difierentiation above referred to, but these circuit-controlling devices may also be used for regulating generally the loudness of the tones produced, and for that purpose they may be operated manually or by means of appropriate perforations inthe music sheet, and either form of device may be constructed and arranged to control any desired number of branch circuits, from one upward. Various other forms of circuit controlling devices may also be employed, if preferred, for opening and closing the branch circuits, or any of them, without departing from my invention.

The particular forms of circuit-controlling devices hereinbefore described are not separately claimed herein, being described and claimed in two divisional applications filed on the 11th day of September, 1914, Serial Nos. 861,318 and 861,319.

- indep resistance, and means for opening and closing said branch circuits independently of each other.

A playing apparatus for musical instrumentscomprising a laying magnet, an energizing circuit thereibr, and means for opening and closing said circuit, a resistance included in said circuit and divided into portions of unequal resistance effect, branch circuits each adapted to short-circuit one of said portions only, and circuit-controlling devices for opening and closing said branch circuits independently of each other.

3.A playlng apparatus for musical instruments, COIIlPIlSlIlg a playing magnet, an

energizing circuit therefor and means for opening and closing said circuit, a resistance included in said circuit, a normally-closed branch circuit. including a contact finger adaptedto slide along said resistance, and a circuit-controlling device for opening and closing said branch circuit.

4. A playing apparatus for musical instruments, comprising a playing magnet, an energizing circuit therefor, and means for included in said circuit and provided with one ormore short-circuiting branch circuits, 9. contact finger adapted to slide along said resistance and included in anormally-closed,

endent branch circuit, and circuit-controlling devices for opening and closing said btrl'tanch circuits independently of one an- 0 er.

5. A playing apparatus for musical instruments, comprising playing magnets arranged in parallel circuits and means for opening and closing said circuits, resistances included in the respective playing-magnet circuits, each resistancebeing provided with a branch circuit adapted to short-circuit a portion only of said resistance, and independent means for progressively varying said resistances and for opening and closing said branch circuits.

6. A playing apparatus for musical instruments, comprising playing magnets arranged in parallel circuits and means for opening and closing said circuits, resistances included in the res e'ctive playing-magnet circuits and" means or short-circuiting different portions of each resistance independently of each other.

-7. A playing apparatus for musical instruments, comprising playing magnets arranged in parallel circuits and means for opening and closing said circuits, resistances included in the respective playing-magnetcircuits, each resistance being divided into two or more portions of unequal resistance effect, and means for short-circuiting the several ortions of each resistance independently 0 one another. 7

8. A playing apparatus for musical instruments, comprising playing magnets arranged in parallel circuits and means for opening and closing said circuits, resistances included in the respective playing-magnet circuits and each provided with a plurality of branch circuits each of which is adapted when closed to short-circuit that portion of the resistance around which it leads, said branch circuits beng arranged in groups, and means for opening and closing simultaneously all the branch circuits in each group independently of those in the other group or groups. 9. A playing apparatus for musical instruments, comprising playing magnets arranged in parallel circuits and means for opening and closing said circuits, resistances included in the respective playing-magnet circuits and each provided with a plurality of branch circuits each of which is adapted to short-circuit a portion only of the corresponding resistance, the branch circuits corresponding to the treble playing-magnet resistances and those corresponding to the bass playing-magnet resistances being arranged in independent groups, and means for opening and closing simultaneously all the branch circuits in each group.

10. A playing apparatus for musical instruments, comprising playing magnets arranged in parallel circuits-and means adapt-- ed to be operated by a perforated music sheet for opening and closing said circuits, resistances included in the respective playingmagnet circuits and each provided with a plurality of branch circuits each of which is adapted to short-circuit a portion only of the corresponding resistance, circuit-controlling devices each arranged to open and close simultaneously a plurality of corresponding branch circuits, and means controlled by special perforations in the music sheet for operating said circuit-controlling devices.

11. A playing apparatus for musical instruments, comprising playing magnets arranged in parallel circultsand means adapted to be operated by a perforated music sheet for opening and closing said circuits, resistances included in the respective playin -magnet circuits and each provided with a ranch circuit adapted to'short-circuit a portion only of the corresponding resistance, circuit-controlling devices each arranged to open and close simultaneously a plurality of said branch circuits, each circuit-controlling device being provided with an electro-magnet for o crating the same, andspecial cir. cuits inc uding the latter magnets respecto short-circuit a portion of the corresponding resistance, the branch .circuits around corresponding resistance portions being arranged in groups, and means for independently opening and closing the' groups of branch circuits comprising circuit-controlling devices, one for each'group, an electromagnet for operating each circuit-control lingdevice,-and'speci'al circuits each includ ing one of said magnets and adapted to be controlled by the music sheet independently of one another.

13. A playing apparatus for musical instruments, comprising playing magnets arranged in parallel clrcuits and means for opening and closingsaid. circuits, resistances included in the respective playing-magnet circuits, sliding contact fingers arranged to be moved along the respective resistances and'included in normally closed branch circuits around the same, and means for opening and closing the branch circuits through said contact fingers.

14. A playing apparatus for musical instruments, comprising playing magnets arranged in parallel circuits and means for opening and closing said circuits, resistances included in the respective-playing magnet circuits and each provided with a branch circuit adapted to short-circuit a portion only of the corresponding resistance, means for opening and closing a plurality of said branch circuits simultaneously, contact fingers movable along the respective resistance and included in' normally-closed branchcircuits around the same, and means for opening and closing the branch circuits through 'sald contact fingers.

15. A playing apparatus for musical instruments, comprisin playing magnets arranged in parallel circuits and means for opening and closing said circuits, resistances included in the respective playing magnet circuits and each provided with one or more short-circuiting branch circuits, means for opening and closing said branch circuits, other branch circuits associated with the respective resistances and including sliding contact fingers adapted to'be moved along said resistances, and means for-openin and closing the branch circuits through sai contact fingers.

16. A playing apparatus for musical instruments, comprismg playin magnets are ranged in parallel circulte an means adapt amass? ed to be operated by a perforated music sheet for opening and closing said circuits, resistances included in the respective playing-magnet circuits and each provided with one or more short-circuiting branch circuits, said branch circuits being arranged in groups, sliding contact fingers arranged to 'be'moved along the respective resistances and included in branch circuits leading around the same, the latter branch circuits "is being also arranged in groups, independently-operable circuit-controlling devices for opening and closing corresponding groups of branch circuits, and means controlled by special perforations in the music sheet for operating said circuit-controlling devices.

17. A playing apparatus for musical instruments, comprising playing magnets arranged in parallel circuits, means for open? ing and closing said circuits, resistances in: cluded in the respective playing-magnet cir-, cuits, each resistance beingprovided with ashort-circuiting branch circuit, and means for controlling said branch circuits compris ing a series of insulated metallic disks mounted on a common shaft, each disk being provided on its periphery with an insulating portion, circuit wires arranged in pairs with the wires of each pair held in contact with one of said disks, and means for partially rotating said shaft to move the insulating portions on the disks into and out of contact with the adjacent circuit wires.

18. A playing apparatus for musical instruments, comprising playing magnets arranged in parallel circuits, means for opening and closing said circuits, resistances included in the respective playing-magnet circuits,each resistance being provided with a short-circuiti branch circuit, and means for controllin said branch circuitsc'omprisin a series 0 insulated metallic disks mounted on a common shaft, each disk being provided on its periphery with an insulating portion,

- circuit wires arranged in pairs with the Wires of each pair held in contact with one of said disks, and means comprising an elec-. tro-magnet and an oscillating armature connected to said shaft for partially-rotating the latter to move the insulating portions on the 11s disks into and out of contact with the adjacent circuit wires.

'19. A playing apparatus for musical instruments, com rising playing ma ets arranged in para el circuits, means or opening and, closing said circuits, resistances included in the respective playing-ma et circuits, each resistance be' provide with .a short-circuiting branch circuit, and means for controlling said branch circuits com ris- 2a ing a series of insulated metallic isks mounted on a common shaft, an insulating rod passing through said series of disks and the periphery of each disk, and means for oscillating said shaft to move the insulating rod into and out of contact with the adjacent circuit wires.

20. A playing apparatus for musical instruments, comprising playing magnets arranged in parallel circuits, means for opening and closing said circuits, resistances included in the respective playing-magnet circuits, each resistance being provided with a short-circuiting branch circuit, and means for controlling said branch circuits comprising a series of metallic disks and a series of insulating disks arranged in alternation and mounted on a common shaft, the insulating disk beingof greater diameter than the metallic disks to provide annular spaces at the periphery of the latter disks and each metallic disk being provided at one point on its periphery with an insulating portion, a pair of circuit wires located in each annular recess in contact with the corresponding me tallic disk, and means for oscillating said shaft to move the insulating portions into and out of contact with the adjacent circuit wires.

In testimony whereof, I have hereunto subscribed my name this 19th day of August, 1910.

WALTER C. REED.

Witnesses:

HARRIET L. Cunrm, GEORGE P, Runs. 

